Upgrade barometer

Upgrading to 9.2.6 requires no downtime.

GitLab EE contains a single migration only used by Geo secondary nodes. We're adding a database-level limit to an integer field for the Geo tracking database.

Please be aware that by default the Omnibus packages will stop, run migrations, and start again, no matter how “big” or “small” the upgrade is. This behavior can be changed by adding a /etc/gitlab/skip-auto-migrations file.